Method of making 2, 2&#39;-biphenyldicarbox-aldehyde



METHOD OF ,ozonation of phenanthrene. f 5640 (1955), ,ozonized phenanthrene in acetic acid and ,in' chloroform. They isolated what they believed to be the mono-ozonide in 85% yield and converted it to diphenaldehyde by pouring the acetic acid solution of the ozonide into four volumes of cold water and allowing the ozonide to hydrolyze at room temperatures over a twoday period. A 43.5% yield of diphenaldehyde, based I on the amount of phenanthrene charged, was obtained.

of a product.

2,942,030 Patented June 21, 1960 MAKINGLT-BIPHENYLDICARBOX- ALDEHYDE Murray G. Shirrock and Edwin L. Cline, Pittsburgh, and

Kenneth R. Robinson, Monroe Heights, Pa., assignors 7 to Koppers Company, Inc., a corporation of Delaware No Drawing. Filed June 26,1958,Ser.No.'7t4,6'38

' 3 Claims. 01. 260-599 This invention relates to a method of making an aromatic dialdehyde derivative from phenanthrene. In one specific aspect, it relates to an ozonation-hydrolysis technique for making diphenaldehyde, 2,2-biphenyldicarboxaldehyde.

Phenanthrene,which comprises 35% of tar recovered abundance of phenanthrene in coal tar and in other source materials, workers in the art have long been in quest of a simple and efficient method for converting phenanthrene into one of its more useful derivatives, e.g. diphenaldehyde;

Asearly as1905, one Harries (Annalen 343,373) attempted to preparederivatives of phenanthrene by the ozonation of the parent compound in chloroform solution. He obtained as a product the explosive phenj anthrene diozonide, but he prepared no further derivatives of that compound.

In recent years, there has been renewed interest in the Schmitt et a1., JACS, 77,

The relatively small yields, the likelihood of the formation, of explosive ozonides,,and the difficulty encountered in the recovery ofv solvent are serious handicaps to commercial development of such a process.

Bailey, JACS, 78, 3811 (1956), ozonized phenanthrene in anhydrous methyl alcohol solution at temperatures between and 60 0, thereby obtaining a 78% yield By 'hydrolyzing this product in 10%' aqueous caustic soda solution, Bailey obtained a 65% over-all yield, based upon the phenanthrene charged, of diphenaldehyde acid (2Fformyl-Z-biphenylcarboxylic acid, MP. 134" C.).v He obtained a 65% over-all yield of i diphenic acid by hydrolyzing the ozonation product in the presence of hydrogen peroxide and caustic. In the course of his work, Bailey also made diphenaldehyde in an 84% over-all yield by ozonation of. phenanthrene in anhydrous methyl alcohol solution, treatment of the ozonation product thus formed with sodium iodide in acetic acid solution, removal of the liberated iodine with sodium thiosulfate and precipitation of the product by manifold dilution with water. While Baileys work resulted in improvement over that of Schmitt et al., the

cost of making the diphenaldehyde by his method is still too high to be regarded as economically attractive. To

a make the diphenaldehyde, he was forced to resort to using sodium iodide, an expensive chemical reducing agent,

in order to obtain his desired product.

United States Patent Ofi Fice removal of the alcohol.

We have discovered a novel method for converting phenanthrene in high yield to diphenaldehyde by a combined ozonation-hydrolysis technique.

It is, therefore, an object of the present'invention to provide a method for making diphenaldehyde in high yield at greatly reduced cost.

In accordance with the invention, phenanthrene is suspended in a medium comprising methyl alcohol and contacted with a gas stream containing ozone to make an ozonation product. This ozonation product is; then hydrolyzed inthe presence of water at a pH below 7.5 to form the diphenaldehyde. Hydrolysis and removal of methyl alcohol from the'system may be accomplished concomitantly. Diphenaldehyde is recovered from the hydrolyzed mixture, generally by solvent extraction, after This application is a continuation-in-part of our copending application SN. 732,081, filed April 30, 1958. In that copending application we disclosed and claimed a method of making ortho-or tho' di-substituted biphenyl derivatives from phenanthrene comprising suspending phenanthrene in a mixture of water and a lower aliphatic alcohol having from 2-4 carbon atoms, contacting the suspension with a gas stream containing ozone to make an ozonation product, and hydrolyzing the ozonation product to form one or more of a series of ortho-ortho' di-substituted biphenyl derivatives. The particular biphenyl derivative obtained depends primarily upon the pH of the reaction mixture during the hydrolysis step. The present invention diifers from that ofour copending application in that herein ozonation is conducted in a medium consisting essentially of anhydrous methyl alcohol or methyl alcohol containing up to 35% by weight water. Thus, for purposes of this invention, an anhydrous alcohol, rather than an alcohol-water medium,

can be used; and if water is present during ozonation, in

contrast with the invention of our copending application,

- of the present invention consists essentially of absolute methyl alcohol or methyl alcohol in admixture with up to 35% water, based upon the total weight of the suspen- 'sion medium. If more than 35% water. is present, the

phenanthrene particles cannot be easily wetted and suspended. If adequate wetting is not attained, the particles tend to float upon the surface of the medium and good contact with ozone cannot be achieved. Obviously, this results in'a greatly diminished yield of product.

Among the lower aliphatic alcohols, methyl alcohol,

since it does not form an azeotrope withwater, is unique.

If ozonation is conducted in anhydrous methyl alcohol, water is added thereafter to eifect hydrolysis. Methyl alcohol boils well below theboiling point of water and, because of this property, it can be readily separated from the hydrolyzed mixture by distillation and reusedin its anhydrous form. Since the other lower aliphatic alcophenanthrene is attained rapidly. Generally, thiefsusthe ozone. ozonize as rapidly as possible. ;avoid a rate of ozone addition greater than the rate of i almost instantaneous. --depend upon the starting quantity of phenanthrene and pension contains between about and 30% by weight phenanthrene.

An oxygen-containing gas is used as a carrier for the ozone during the reaction.- The type of gaseous carrier and the concentration of ozone therein depends upon the type of equipment used. Certain generators provide a stream of ozone in air in concentrations ranging from 0.58% by weight. Others provide ozone in oxygen,'the concentration of ozone being between 2. and 16% by weight. The entire gamut of ozone concentrations provided by either type of generating equipment is suitable for purposes of the present invention.

It is of utmost importance to provide intimate contact between the ozone and the phenanthrene. Conventional equipment maybe used to disperse the ozone in the phenanthrene suspension.

It is preferable to introduce the ozone-containing gas in the form of small bubbles to insure intimacy of contact. The rate of ozone addition is determined by the ability of the phenanthrene to absorb It is, ofcourse, commercially desirable to Care should be taken to absorption of the ozone by the reaction mixture. Usage of ozone-in this manner is obviously wasteful. Moreover, explosive mixtures of gases may be formed in the equipment. The rate of ozone addition may be conveniently governed by an ozone meter placed downstream from the reaction mixture to determine whether all of the ozone added is being absorbed.

To obtain high yields of diphenaldehyde by the methods of the present invention, it is desirable to use at least a "stoichiometric quantity of ozone based upon the starting amount of phenanthrene (a 1:1 mol ratio).

The reaction between ozone and the phenanthrene is The reaction time will, therefore,

the intimacy of the contact between ozone and the phenanthrene. The reaction is continued until the desired quantity of ozone has been absorbed. I

The reaction is conducted at atmosphere pressure (although higher or lower pressures can be used) over a temperature range of, for example, -20' to 40 C. The lower limit is established by the freezing point of the particular medium used- Operation at temperatures below those conveniently obtained with cooling water is possible, but generally the increased ozone solubility obtainable by this means cannot justify the high equipment costs involved. The upper limit is the boiling point of the solvent at the pressure used. It is less expensive, and therefore preferable, to conduct the reaction at ambient temperaturesc An important feature of the present invention is the 1 particular set of conditions used during the hydrolysis step. .If absolutemethyl alcohol is used as a solvent, it is necessary to add water to the reaction. mixture after the ozonation has been completed. The amount of water i added must be at least sufficient to effect hydrolysis, i.e.

1 mol of water for each mol of ozonation product. There is no particular upper limit on the amount of water to be added, although it is obviously inconvenient during processing to handle excessive volumes of water.

. .veniently, an amount of water equal to the weight of the suspension medium is added. If the suspension medium for ozonation contains an amount of water sufiicient for hydrolysis, obviously no water need be added.

Con-

-In the present invention, pH control of the reaction .smixture during hydrolysis is of paramount importance.

If the pH of the mixture is maintained below about 7.5,

.diphenaldehyde is obtained as a product in yields of 90% and higher. This result is quite astonishing in view of the teachings of the art. For example, Bailey, supra, resorted to treatment of his ozonation product with the expensive reagent, sodium iodide, in acetic acid solution to obtain an i 84% yield of diphenaldehyde. The pH of the reaction .mixture. cluring the hydrolysisstep is easily maintained at below about 7.5 by avoiding the addition. Of any substan- Since it is unnecessary tohydrolyze under totalffreflux,

methyl alcohol is conveniently'dis'tilled over'a'lmost immediately after the reaction mixtureis brought to the required temperature for hydrolysis. Hydrolysis and distillation can be accomplished under vacuum, but it is obviously preferable to work at atmospheric pressure because of equipment costs involved. Hydrolysis and distillation can be accomplished in separate steps by first extremely stable to oxidation. It

hydrolyzing the ozonation product at a temperature somewhat below the boiling point (or under total reflux) and thereafter distilling off the suspension medium. No particular advantage is seen in such a technique. After the 'methyl alcohol is removed, the diphenaldehyde is recovered from the remaining aqueous solution by decantation or by extraction with common organic solvehts such as benzene, carbon tetrachloride, toluene, and, the like. Evaporation of the solvent extract yields diphenaldehyde as a yellow solid. 1

Any phenanthrene impurity can be removedfrom the product by distillation, recrystallization, or conversion of the diphenaldehyde to its sodium bisulfite adduct with'subsequent separation by extraction or filtration.

The aqueous solution from which the diphenaldehyde has been recovered'contains up to about 75% of theory .of hydrogen peroxide. Thus, our process not only provides good yields of the desired diphenaldehyde, but, in addition, high yields of a valuable by-product, hydrogen peroxide, are obtained. H

Unlike other aromatic aldehydes, diphenaldehyde is is not oxidized by air or by hydrogen peroxide; and peracetic acid attacks it only very slowly. Treating diphenaldehyde with boiling nitric acid, or chlorine, converts it to 9,10-phenanthraquit1one in about yield. When diphenaldehyde is heated at pH above 10, it undergoes an intra-molecular Cannizzaro reaction to form the alcohol-acid, Z-hydroxymethyl2-biphenylcarboxylic acid. This latter compound isconverted almost quantitatively to diphenic acid in the presence of boiling concentrated nitric acid. f Diphenaldehyde is readily reduced as, for example, by lithium aluminum hydride to form the corresponding dialcohol, 2,2-biphenyl-dimethanol. The dialdehyde is readily condensed withphenolsto give a light-fast dyestuff analogousto the dyes of the triphenylmethane series. When heatedwith urea, diphenaldehyde forms insoluble, infusible condensation products useful as ion exchange resins. Diphenaldehyde is particularly adaptable for uses wherein stability againstoxidation is desirable, e.g. in perfume manufacture and in the making of light screening agents.

Our invention is further illustrated by the following examples.

Example 1 Five parts (0.028 mol) of phenanthrene wereslurried with 100 parts of methyl alcohol. An oxygen stream containing 4.12% ozone was introduced at a rate of 0.405 part per minute. The temperature of the reaction mixture was maintained in the range of 0 to 20.C. during the absorption of the ozone. A total of 0.0322 mol of ozone was introduced, of which only a negligible amount was recovered in the potassium iodide trap.

One hundred ml. of ice water were added and the ozonation product was hydrolyzed bp heating the mixture to its boiling point. The alcohol was recovered concomitantly by distillation. 'As the alcohol was removed,

--'a'yellow oil, which-solidified partially upon cooling, begank to' separate from. the aqueous solution. This oil was completely separated from the solution by repeated of. theory, based upon the weight of phenanthrene charged.

The remaining aqueous solution was found to contain active oxygen. The solution was treated with dilute sulfuric acid and potassium iodide and the iodine thus liberated was then titrated with sodium thiosulphate. The results of the titration showed that the aqueous solution contained hydrogen peroxide in an amount equal to 73% of theory.

Example II Five parts (-0.028 mol) of phenanthrene were dissolved in 100 parts of hot methyl alcohol and the solution was thereafter rapidly cooled to -20 C. with vigorous stirring. This mixture was then ozonized with an oxygen stream containing 3.91% ozone. The ozone-oxygen mixture was introduced at the rate of 0.405 part per minute. The reaction mixture was kept at a temperature of 0 C. to --20 C. during the ozonation. A total of 0.0322 mol of ozone was introduced, of which only a negamp Y Five parts (0.028 mol) of phenanthrene were dissolved in 70parts of hot methyl alcohol and this solution was added to 30 parts of ice cold water with vigorous' stirring. This slurry was then ozonized at room temperature .with an oxygen stream containing 7.62%

i'ozone. The ozone-oxygen mixture was' introduced at the rate of 0.81 partper minute. A total 'of"0.0333 mol of clone was introduced, of which 0.0011 mol passed ligible amount was recovered in the potassium iodide trap.

One hundred ml. of ice water was added to the reaction mixture (pH about 3.5) and the ozonation product was hydrolyzed by heating the mixture to its boiling point. The alcohol was removed concomitantly by distillation. As the alcohol was removed, a yellow oil separated and solidified partially on cooling. The organic material was removed from the aqueous solution by benzene extraction. Evaporation of the benzene extract yielded 5.9 parts of a yellow oily solid, which contained no active oxygen. The oily solid (5.4 parts) was extracted with sodium bisulfite solution and yielded 0.3 part of insoluble material consisting essentially of phenanthrene (representing a 93.5% ozone attack on the phenanthrene charged). The sodium bisulfite soluble material amounted to 5.0 parts (98.2% yield based on the phenanthrene reacted or 92.4% based on the phenanthrene charged) and was shown to be essentially diphenaldehyde by infrared analysis.

Example III Five parts (0.028 mol) of phenanthrene were dissolved in 88 parts of methyl alcohol by Warming, and this solution was added to 12 parts of ice water with vigorous stirring. This mixture was then ozonized at room temperature with an oxygen stream containing 7.89% ozone. The ozone-oxygen mixture was introduced at the rate of 0.81 part per minute. A total of 0.0323 mol of ozone was introduced, of which 0.0001 mol passed through the reaction mixture and was recovered in the potassium dioxide trap. b

After ozonation, the reaction mixture (at a pH of 1.5) was diluted with 38 parts of water. The mixture was heated to its boiling point to effect hydrolysis of the ozonation product and the methyl alcohol removed simultaneously by distillation. The organic material was recovered by extraction with benzene. Evaporation of the benzene yielded 5.9 parts of a yellow oil, which contained no activeoxygeu. The oil (5.8 parts) was extracted with sodium bisulfite solution and yielded 0.1 part of insoluble material consisting essentially of phenanthrene (representing 98% attack on the phenanthrene charged). The sodium bisulfite soluble material amounted to 5.5 parts (96.8% yield based on phenanthrene reacted or 96.4% based on the phenanthrene charged), and was sis.

through the reaction mixture and was recovered in the potassium iodide trap.

After ozonation, the reaction mixture (at a pH of 2.0) was diluted with 20 parts of water and heated to its boiling point to elfect hydrolysis. The methyl alcohol was removed simultaneously by distillation. The organic material was removed by extraction with benzene. Evaporation of the benzene yielded 5.9 parts of a yellow orange oil, which contained no active oxygen. The oil (5.7 parts) was extracted with sodium bisulfite solution and yielded 0.5 part of insoluble material consisting essentially of phenanthrene (an ozone attack of based on the phenanthrene charged). The sodium bisulfite soluble material amounted to 4.9 parts (95.7% yield based on the phenanthrene reacted or 86% based on the phenanthrene charged), and was shown to be essentially diphenaldehyde by infrared analysis.

Example V Five parts (0.028 mol) of phenanthrene were dissolved in 50 parts of hot methyl alcohol and this solution was added to 50 parts of ice cold water with vigorous stirring. This slurry was then ozonized at room temperature with an oxygen stream containing 7.9% ozone. The ozone-oxygen mixture was introduced at the rate of 0.81 part per minute. A total of 0.0443 mol of ozone was introduced, of which 0.0121 mol passed through thereaction mixture and was removed in the potassium iodide trap.

After ozonation, the reaction mixture (having a pH of 2.0) was hydrolyzed by heating and simultaneously distilled to remove the methyl alcohol. The organic material was removed by extraction with benzene. Evaporation of the benzene yielded 5.3 parts of a yellow oily solid, which contained no active oxygen. The yellow oily solid (5.1 parts) was extracted with sodium bisulfite solution and yielded 2.1 parts of insoluble material consisting essentially of phenanthrene (an ozone attack of 55% based on the phenanthrene charged). The sodium bisulfite soluble material amounted to 2.9 parts (51% yield based on the phenanthrene charged), and was shown to be essentially diphenaldehyde by infrared analysis. The considerable reduction in the yield obtained indicated that an excess of water (viz: 50% by weight) cannot be present during the ozonation step.

We claim:

1. In a method of making diphenaldehyde wherein ozone is contacted with phenanthrene in the presence of methyl alcohol to form an ozonation product, the improvement comprising heating the ozonation product in the presence of water at a pH below 7.5 to effect hydrolytic decomposition of said product to form diphenaldehyde and hydrogen peroxide, distilling off said alcohol in substantially anhydrous form, and separating diphenaldehyde from the reaction mixture.

2. In a method of making diphenaldehyde wherein ozone is contacted with phenanthrene in the presence of methyl alcohol to form an ozonation product, the improvement comprising contacting phenanthrene, susoxide, concomitantly"distilling' off said alcohol in substantially guhydrous forng, and separating liphenalde- .hyde from. the hydrogen peroxide by solyent extraction.

3. In a rnethod of jmaki g diphepgldehyde wherein 9. 91 is qn as fi d wi h li len thf v suspndedin m hy alcohol to ionn arl ozonation' product, the irh proyerhent r pmn 'l 'in t ad i Wa 21 1 1 s pnn m w e ing ,the ozouati on product, heating the resulting rhixtu re at a below 7.5 -to effect hydrolytic decomposition of "said; ozofiatiomproducf'to foim diphenzildehyde ancLhydroge'n peroxide; distilling off said alcohol in substantially References Cited in the file of this pte'ut Bailey: Jour.Amer."Chern. Soc., vol. 78 (1956), pgs. 3811-3816. 

1. IN A METHOD OF MAKING DIPHENALDEHYDE WHEREIN OZONE IS CONTACTED WITH PHENANTHRENE IN THE PRESENCE OF METHYL ALCOHOL TO FORM AN OZONATION PRODUCT, THE IMPROVEMENT COMPRISING HEATING THE OZONATION PRODUCT IN THE PRESENCE OF WATER AT A PH BELOW 7.5 TO EFFECT HYDROLYTIC DECOMPOSITION OF SAID PRODUCT TO FORM DIPHENALDEHYDE AND HYDROGEN PEROXIDE, DISTILLING OFF SAID ALCOHOL IN SUBSTANTIALLY ANHYDROUS FORM, AND SEPARATING DIPHENALDEHYDE FROM THE REACTION MIXTURE. 